Visit a website such as Coinflation.com or CoinStudy to gain an approximate value of an old silver coin as a collectible and in melt value for the silver. For example, a Morgan silver dollar has $12.85 of silver when melted down, as of 2015.
In terms of collectibles, the value of old silver coins varies depending on the number of coins that were originally minted, the number still known to be available and the condition of the coin. For example, the 1878 Morgan silver dollar minted in Philadelphia but bearing no mint mark had a run of more than 10.5 million coins. As of 2015, the value of that coin as a collectible starts at $23 in good condition and goes as high as $50 if the coin is uncirculated. However, that same year, only about 2.2 million Morgan silver dollars were minted in Carson City and bear a CC mint mark. Values for those coins range from $65 in good condition to $180 and up for uncirculated coins.
The 1893 Morgan silver dollar minted in San Francisco has the highest value of that coin's run if uncirculated, starting at $90,000 due to the scarcity of the coins that are still available.